In mobile telecommunications networks, event reporting may be used for providing inputs to certain control processes. For example, in 3GPP (3rd Generation Partnership Project) mobile networks, e.g., GSM (Global System for Mobile communications), UMTS (Universal Mobile Telecommunications System), or LTE (Long Term Evolution) networks, a reported event may trigger establishment or configuration of a bearer for carrying data of a packet based service to or from a user equipment (UE).
In 3GPP mobile networks, a policy and charging control (PCC) architecture as defined in 3GPP Technical Specification 23.203 may be provided so as to support such event reporting and control processes. This PCC architecture may be used for controlling various types of radio access technology (RAT) and corresponding radio access networks, including 3GPP accesses such as GERAN (GSM Radio Access Network), UTRAN (UMTS Terrestrial Radio Access Network) and E-UTRAN (Evolved UTRAN), and non-3GPP accesses, e.g., based on WLAN (Wireless Local Area Network). In the following, such designations of radio access networks will also be used to designate the underlying RAT. One type of event which may be reported in a mobile network implementing two or more of such RAT types may be a change of the RAT type used by the UE for connecting to the mobile network. Other events which may be reported are for example changes in the location of the UE. In such cases, for example a node referred to as Policy and Charging Rules Function (PCRF) may subscribe to reporting of such events by a node referred to as Policy and Charging Enforcement Function (PCEF). If the specified type of event is detected by the PCEF, the PCEF reports the event to the PCRF.
For certain control processes, the PCRF may obtain input information by subscribing to event reporting by the PCEF. For example, some policies applied by the PCRF may depend on whether the UE presently uses a specific RAT type, e.g., E-UTRAN, and therefore subscribe to reporting of RAT type changes by the PCEF. The reported RAT type change may at the same time also indicate the new RAT type. For example, establishing dedicated bearers may be supported only in E-UTRAN, and through reporting of RAT type changes the PCRF may become aware whether the UE uses E-UTRAN for accessing the mobile network or not. Based on this information, the PCRF may for example decide whether to initiate establishment of a new dedicated bearer (if the presently used access is E-UTRAN) or to modify an existing default bearer (if the presently used access is not E-UTRAN) so as to provide a desired Quality of Service (QoS) for data traffic to or from the UE.
However, the above way of learning about the current status of the UE through reported events may in some cases be inefficient or even not possible. For example, in some scenarios there may be a large amount of handovers between GERAN and UTRAN, e.g., if a high load in the UMTS network part or certain environmental factors, e.g., dense buildings, cause temporal or local variations in UMTS coverage.
Accordingly, there is a need for techniques which allow for efficiently reporting events in a mobile telecommunications network.